I tried different things and after all I’ve just switched to my own emulated hue bridge, calling reactor HTTP endpoints. I was toying with the idea of sending MQTT commands, but HTTP just works. I did my own bridge because I have 100 switches/scenes/virtual switches mapped to Alexa and ha-bridge has not the ability to define multiple bridges on the same host, so I wrote mine 
But ha-bridge should just work. Never tried HASS native hue emulation. I tried matter bridge and unfortunately Alexa will only see 20 devices.